Chagas Disease

National Organization for Rare Disorders, Inc.

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  • American Trypanosomiasis
  • Brazilian Trypanosomiasis

Disorder Subdivisions

  • None

General Discussion

Chagas Disease is a tropical infectious disease caused by the parasite Trypanosoma cruzi. It is transmitted by the bite of one of several species of blood-sucking insects or by blood transfusion. Acute Chagas Disease usually affects children and typically presents as the mild phase of the disease. However, this is generally followed by a long period of low level, parasitic infection (parasitemia). Many years later, about 10 to 30 percent of people with Chagas Disease develop the more severe symptoms associated with "chronic" Chagas Disease. The heart and digestive systems are most frequently involved in this phase of the disease. The most common features of late chronic Chagas Disease include abnormal enlargement of the esophagus (megaesophagus) and colon (megacolon), and congestive heart failure. Chagas Disease occurs primarily in Central and South America.


Chagas Disease occurs as "acute" or prolonged "chronic" disease. The symptoms of acute Chagas Disease typically begin as a reaction at the location of the insect bite (inoculation site) which becomes swollen and inflamed (chagoma). Occasionally the parasite may enter the body through the membranes that line the eye (conjunctiva). This may occur when affected individuals scratch the area of the bite and then rub their eye. Excessive swelling of the area around one eye (unilateral periorbital edema) is known as "Romana's sign" and is characteristic of Chagas Disease.

Early symptoms of Chagas Disease may include an abnormally elevated fever, a general feeling of ill health (malaise), skin rashes, and/or the excessive accumulation of fluid in the legs and face (edema). Some people with this disease may also have swollen and painful lymph nodes (lymphadenopathy) and/or an abnormally enlarged liver and spleen (hepatosplenomegaly).

In severe cases of Chagas Disease, acute inflammation may occur in the membranes that line the brain (meningoencephalitis) and in the muscular middle layer of the heart (myocarditis). These conditions usually resolve on their own without treatment and no symptoms may be apparent during this phase (indeterminate stage). T. cruzi parasites are still present in the blood (parasitemia) and may be transmitted to others by blood transfusion. In some individuals myocarditis and meningoencephalitis may cause life-threatening complications.

Approximately 10 to 30 years after the initial infection most people with Chagas Disease develop the chronic form of the disease. Complications typically relate to the abnormal enlargement of the heart (dilated cardiomyopathy) due to the overgrowth of fibrous tissue (diffuse myocardial fibrosis) and the loss of muscle tissue within the heart (myocardial atrophy). Symptoms may include swelling of the arms, legs, and face, periodic loss of consciousness (syncope), an abnormally slow heartbeat (bradycardia), an irregular heartbeat (arrhythmia), difficultly breathing (dyspnea), blockage of a blood vessel due to a blood clot (thromboembolism), and/or congestive heart failure.

The chronic stage of Chagas Disease is also characterized by the abnormal enlargement of the esophagus (megaesophagus). Symptoms may include difficulty swallowing (dysphagia), chest pain, regurgitation of food into the mouth, and/or aspiration of food into the lungs. Abnormal enlargement of the colon (megacolon) may produce abdominal pain and discomfort, constipation, twisting of the bowel (volvulus), and/or intestinal obstruction.


Chagas Disease is a rare tropical infectious disease caused by the single- celled organism (protozoa) Trypanosoma cruzi. Symptoms develop due to the presence of the parasite in the blood stream and within the cells of various organs of the body, especially the heart and intestines.

Affected Populations

Chagas Disease is a tropical infectious disease that affects males and females in equal numbers. It is transmitted by the bite of reduviid bugs. When a person is bitten by a reduviid bug, the insect releases feces on the site of the bite. The feces contain T. cruzi organisms which are released into the blood stream when affected individuals scratch the bite.

Reduviid bugs are found most commonly in the rural areas of Latin America. They tend to inhabit woodpiles and thatched, mud, or cane houses. The acute form of Chagas Disease occurs most frequently in children who live in these areas. However, the major route of transmission in urban areas is by transfusion with blood that is contaminated with the organism.

Chagas Disease is a very common infectious disease in Central and South America. It is estimated that approximately 24 million people are infected with this parasite in these regions. Research indicates that infection does not occur in the United States through reduviid bug transmission because the feces do not contain the infectious parasite in North America. However, transmission of Chagas Disease has occurred in the United States via blood transfusions. With increasing numbers of immigrants from areas of active T. cruzi infection (endemic regions), transfusion-associated Chagas Disease may become a more significant problem in the United States.

Studies suggest that the North American insect responsible for trypanosomiasis could prove to be a likely carrier (vector) for future cases of Chagas Disease in the United States. Many different animals in the southern United States are infected with the T. cruzi parasite and may ultimately infect an insect such as trypanosomiasis. Other insects carrying the parasite may also be introduced at any time into North America from endemic areas.

The symptoms of the chronic phase of Chagas Disease may be worse in those individuals with a compromised immune system due to certain drugs or diseases that weaken their ability to fight infections.

Chagas disease affects between 16 million and 18 million people worldwide.

Standard Therapies

In the acute stage, Chagas Disease may be diagnosed by microscopic examination of fresh blood, or thick and thin blood smears which confirms the presence of the parasite along with characteristic cardiac and intestinal symptoms. Chronic Chagas Disease may be confirmed by specialized blood tests such as enzyme-linked immunosorbent assay (ELISA) or complement fixation tests that demonstrate antibodies to T. cruzi.

Acute Chagas Disease should be treated early with antiparasitic drugs such as nifurtimox (a derivative of nitrofurazone) or benzimidazole which may destroy some of the infectious parasites in the body. While these drugs may reduce the severity of the parasitic infection, they are not considered curative. In most cases the parasite does survive and chronic infection (parasitemia) occurs.

When Chagas Disease affects the heart, the drug amiodarone may be effective in controlling irregular heartbeats (arrhythmias). Drugs that thin the blood and reduce clotting ability (anticoagulation therapy) may be of some benefit in the prevention of recurrent episodes of clots that travel in the blood stream (thromboemboli).

There are no satisfactory antimicrobial or antiparasitic drugs for the treatment of the indeterminate and chronic stages of Chagas Disease. No drug can reverse the damage done to various organs of the body. Other treatment is symptomatic and supportive.

Chagas Disease can be prevented by eliminating the insect that transmits the disease. Various insecticides such as gamma-benzene hexachloride can be used to spray houses. Improvements in housing, such as wood and masonry construction, may also be helpful in preventing transmission of Chagas Disease in endemic areas of South and Central America.

Investigational Therapies

The orphan drug allopurinol riboside is currently undergoing clinical trials for the treatment of chronic Chagas Disease. More studies are needed to determine the long-term safety and effectiveness of this drug for the treatment of Chagas Disease. For more information, physicians can contact:

Burroughs Wellcome Co.

3030 Cornwallis Rd.

Research Triangle Park, NC 27709

The French pharmaceutical manufacturer Fournier is developing the drug LF1695 to enhance the immune systems of children with Hodgkin's Disease, Shwachman Syndrome, and Chagas Disease. For more information, physicians may contact:

Fournier Labs

BP90, Daix 21121

Fontaine Les Dijon, France

Information on current clinical trials is posted on the Internet at All studies receiving U.S. Government funding, and some supported by private industry, are posted on this government web site.

For information about clinical trials being conducted at the NIH Clinical Center in Bethesda, MD, contact the NIH Patient Recruitment Office:

Tollfree: (800) 411-1222

TTY: (866) 411-1010


For information about clinical trials sponsored by private sources, contact:



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